There has been a bit of discussion in other threads about how the 450FX shrouds differ from the 450F but just wanted to start a new topic to make it more searchable in the future.
I purchased a 450F graphics kit for my 450FX knowing that there were some "minor" differences between the radiator shrouds. Come to find out, when I just placed the graphics over the FX shrouds there was just no way to trim them and make them work. You'll notice that not only are the FX shrouds longer in the front, but they are also "chopped" in the back.
So I set out to understand what the differences were and hopefully this is of some benefit to others.
What I ended up doing is purchasing a 2015 YZ250FX full Acerbis plastic kit. This kit contains the FX rear fender to accommodate the FX battery while also coming with the standard "F" radiator shrouds. The perfect mix.
Just to summarize:
If you want to make 450F graphics work on a 450FX you can purchase 250/450F or 250FX shrouds. And if you are in search of a full plastics kit, go with a 250FX setup.